ML20080K558
| ML20080K558 | |
| Person / Time | |
|---|---|
| Site: | 05000142 |
| Issue date: | 02/13/1984 |
| From: | Wegst W CALIFORNIA, UNIV. OF, LOS ANGELES, CA |
| To: | NRC |
| References | |
| NUDOCS 8402160059 | |
| Download: ML20080K558 (1) | |
Text
UNIVERSITY OF CALIFO11NIA, LOS ANGELES UCLA f
SANT4 84RBAR4
- SANTA CRUZ 1R% 3NE
- LO$ ANGELES
- RIVERilDE = 54N DIEGO + $4N FRANCl5CO SEREELET a D4Vil COMMUNITY SAFETY DEPARTMENT OFFICE OF RESEARCII & OCCUPATIONAL SAFETY IDS ANGELES, CALIFORNIA 90094 13 February 1984 Director Division of Operating Reactors United States Nuclear Regulatory C6ninission Washington, D.C.
20555 Docket: 50-142
Dear Sir:
During the annual reactor calibrations, it was found that two of the control blades exhibited prolonged drop times, one approaching the acceptability limit and one slightly exceeding the limit.
A preliminary investigation has revealed that the problem resides within the core and not in the external drive trains. Manual torquing of the shafts suggests a thickening of the lubricant in the rod support bearings. There is no indication of roughness or points of hengup, but rather a steady viscous drag.
It is well known that lubricants deteriorate in radiation fields. This kind of rod behavior has been observed previously at UCLA and was expected to recur although the life of the lubricant and hence the timing of the phenomenon was unknown.
-This report is filed in -compliance with our Technical Specification VIII.M.2.e.
All reactor operations have been suspended pending correction of the problem.
Sincerely, d
Walter F. Wegst, Director Office of Research &
WFW/NC0/jb Occupational Safety 8402160059 840213 0
PDR ADOCK 05000142 9
S PDR g
b,
,